/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j;

import org.apache.log4j.spi.Filter;
import org.apache.log4j.spi.ErrorHandler;
import org.apache.log4j.spi.LoggingEvent;

/**
 * Implement this interface for your own strategies for outputting log
 * statements.
 * 
 * @author Ceki G&uuml;lc&uuml;
 */
public interface Appender {

	/**
	 * Add a filter to the end of the filter list.
	 * 
	 * @since 0.9.0
	 */
	void addFilter(Filter newFilter);

	/**
	 * Returns the head Filter. The Filters are organized in a linked list and
	 * so all Filters on this Appender are available through the result.
	 * 
	 * @return the head Filter or null, if no Filters are present
	 * @since 1.1
	 */
	public Filter getFilter();

	/**
	 * Clear the list of filters by removing all the filters in it.
	 * 
	 * @since 0.9.0
	 */
	public void clearFilters();

	/**
	 * Release any resources allocated within the appender such as file handles,
	 * network connections, etc.
	 * 
	 * <p>
	 * It is a programming error to append to a closed appender.
	 * 
	 * @since 0.8.4
	 */
	public void close();

	/**
	 * Log in <code>Appender</code> specific way. When appropriate, Loggers will
	 * call the <code>doAppend</code> method of appender implementations in
	 * order to log.
	 */
	public void doAppend(LoggingEvent event);

	/**
	 * Get the name of this appender. The name uniquely identifies the appender.
	 */
	public String getName();

	/**
	 * Set the {@link ErrorHandler} for this appender.
	 * 
	 * @since 0.9.0
	 */
	public void setErrorHandler(ErrorHandler errorHandler);

	/**
	 * Returns the {@link ErrorHandler} for this appender.
	 * 
	 * @since 1.1
	 */
	public ErrorHandler getErrorHandler();

	/**
	 * Set the {@link Layout} for this appender.
	 * 
	 * @since 0.8.1
	 */
	public void setLayout(Layout layout);

	/**
	 * Returns this appenders layout.
	 * 
	 * @since 1.1
	 */
	public Layout getLayout();

	/**
	 * Set the name of this appender. The name is used by other components to
	 * identify this appender.
	 * 
	 * @since 0.8.1
	 */
	public void setName(String name);

	/**
	 * Configurators call this method to determine if the appender requires a
	 * layout. If this method returns <code>true</code>, meaning that layout is
	 * required, then the configurator will configure an layout using the
	 * configuration information at its disposal. If this method returns
	 * <code>false</code>, meaning that a layout is not required, then layout
	 * configuration will be skipped even if there is available layout
	 * configuration information at the disposal of the configurator..
	 * 
	 * <p>
	 * In the rather exceptional case, where the appender implementation admits
	 * a layout but can also work without it, then the appender should return
	 * <code>true</code>.
	 * 
	 * @since 0.8.4
	 */
	public boolean requiresLayout();
}
